= form_tag do
  = field_set do
    = field ProductPhase.human_attribute_name(:variant), selector_tag(:variant_id, {controller: :product_nature_variants, action: :unroll, scope: {of_variety: :animal}}, value: params[:variant_id], new: backend_product_nature_variant_path)
    = field ProductPhase.human_attribute_name(:started_at), datetime_field_tag(:started_at)
    = field Intervention.human_attribute_name(:production), selector_tag(:activity_production_id, {controller: :activity_productions, action: :unroll, scope: {of_current_campaigns: true} }, value: params[:activity_production_id])
  = form_actions do
    = submit_tag :add_to_variant.ta
